gsElTimeIntegrator.hpp

/** @file gsElTimeIntegrator.hpp

    @brief A class providing time integration for dynamical elasticity.

    This file is part of the G+Smo library.

    This Source Code Form is subject to the terms of the Mozilla Public
    License, v. 2.0. If a copy of the MPL was not distributed with this
    file, You can obtain one at http://mozilla.org/MPL/2.0/.

    Author(s):
        O. Weeger    (2012 - 2015, TU Kaiserslautern),
        A.Shamanskiy (2016 - ...., TU Kaiserslautern)
*/

#pragma once

#include <gsElasticity/gsElTimeIntegrator.h>

#include <gsElasticity/gsElasticityAssembler.h>
#include <gsElasticity/gsMassAssembler.h>
#include <gsElasticity/gsIterative.h>

namespace gismo
{

template <class T>
gsElTimeIntegrator<T>::gsElTimeIntegrator(gsElasticityAssembler<T> & stiffAssembler_,
                                          gsMassAssembler<T> & massAssembler_)
    : stiffAssembler(stiffAssembler_),
      massAssembler(massAssembler_)
{
    initialized = false;
    m_options = defaultOptions();
    m_ddof = stiffAssembler.allFixedDofs();
    numIters = 0;
    hasSavedState = false;
    solVector = gsMatrix<T>::Zero(stiffAssembler.numDofs(),1);
    velVector = gsMatrix<T>::Zero(massAssembler.numDofs(),1);
    accVector = gsMatrix<T>::Zero(massAssembler.numDofs(),1);
}

template <class T>
gsOptionList gsElTimeIntegrator<T>::defaultOptions()
{
    gsOptionList opt = Base::defaultOptions();
    opt.addInt("Scheme","Time integration scheme",time_integration::implicit_linear);
    opt.addReal("Beta","Parameter beta for the time integration scheme, see Wriggers, Nonlinear FEM, p.213 ",0.25);
    opt.addReal("Gamma","Parameter gamma for the time integration scheme, see Wriggers, Nonlinear FEM, p.213 ",0.5);
    opt.addInt("Verbosity","Amount of information printed to the terminal: none, some, all",solver_verbosity::none);
    return opt;
}

template <class T>
void gsElTimeIntegrator<T>::initialize()
{
    stiffAssembler.assemble(solVector,m_ddof);
    massAssembler.assemble();
    gsSparseSolver<>::SimplicialLDLT solver(massAssembler.matrix());
    accVector = solver.solve(stiffAssembler.rhs().middleRows(0,massAssembler.numDofs()));
    initialized = true;
}

template <class T>
void gsElTimeIntegrator<T>::makeTimeStep(T timeStep)
{
    if (!initialized)
        initialize();

    tStep = timeStep;
    if (m_options.getInt("Scheme") == time_integration::implicit_linear)
        newSolVector = implicitLinear();
    if (m_options.getInt("Scheme") == time_integration::implicit_nonlinear)
        newSolVector = implicitNonlinear();
    oldVelVector = velVector;
    dispVectorDiff = (newSolVector - solVector).middleRows(0,massAssembler.numDofs());
    velVector = alpha4()*dispVectorDiff + alpha5()*oldVelVector + alpha6()*accVector;
    accVector = alpha1()*dispVectorDiff - alpha2()*oldVelVector - alpha3()*accVector;
    solVector = newSolVector;
}

template <class T>
gsMatrix<T> gsElTimeIntegrator<T>::implicitLinear()
{
    if (massAssembler.numDofs() == stiffAssembler.numDofs())
    {   // displacement formulation
        m_system.matrix() = alpha1()*massAssembler.matrix() + stiffAssembler.matrix();
        m_system.matrix().makeCompressed();
        m_system.rhs() = massAssembler.matrix()*(alpha1()*solVector.middleRows(0,massAssembler.numDofs())
                                                 + alpha2()*velVector + alpha3()*accVector) + stiffAssembler.rhs();
    }
    else
    {   // displacement-pressure formulation
        m_system.matrix() = stiffAssembler.matrix();
        tempMassBlock = alpha1()*massAssembler.matrix();
        tempMassBlock.conservativeResize(stiffAssembler.numDofs(),massAssembler.numDofs());
        m_system.matrix().leftCols(massAssembler.numDofs()) += tempMassBlock;
        m_system.matrix().makeCompressed();
        m_system.rhs() = stiffAssembler.rhs();
        m_system.rhs().middleRows(0,massAssembler.numDofs()) +=
                massAssembler.matrix()*(alpha1()*solVector.middleRows(0,massAssembler.numDofs())
                                        + alpha2()*velVector + alpha3()*accVector);
    }

#ifdef GISMO_WITH_PARDISO
    gsSparseSolver<>::PardisoLDLT solver(m_system.matrix());
    return solver.solve(m_system.rhs());
#else
    gsSparseSolver<>::SimplicialLDLT solver(m_system.matrix());
    return solver.solve(m_system.rhs());
#endif
    numIters = 1;
    return gsMatrix<T>();
}

template <class T>
gsMatrix<T> gsElTimeIntegrator<T>::implicitNonlinear()
{
    gsIterative<T> solver(*this,solVector);
    solver.options().setInt("Verbosity",m_options.getInt("Verbosity"));
    solver.options().setInt("Solver",linear_solver::LDLT);
    solver.solve();
    numIters = solver.numberIterations();
    return solver.solution();
}

template <class T>
bool gsElTimeIntegrator<T>::assemble(const gsMatrix<T> & solutionVector,
                                     const std::vector<gsMatrix<T> > & fixedDoFs)
{
    stiffAssembler.assemble(solutionVector,fixedDoFs);
    if (massAssembler.numDofs() == stiffAssembler.numDofs())
    {   // displacement formulation
        m_system.matrix() = alpha1()*massAssembler.matrix() + stiffAssembler.matrix();
        m_system.matrix().makeCompressed();
        m_system.rhs() = stiffAssembler.rhs() +
                         massAssembler.matrix()*(alpha1()*(solVector-solutionVector) + alpha2()*velVector + alpha3()*accVector);
    }
    else
    {   // displacement-pressure formulation
        m_system.matrix() = stiffAssembler.matrix();
        tempMassBlock = alpha1()*massAssembler.matrix();
        tempMassBlock.conservativeResize(stiffAssembler.numDofs(),massAssembler.numDofs());
        m_system.matrix().leftCols(massAssembler.numDofs()) += tempMassBlock;
        m_system.matrix().makeCompressed();
        m_system.rhs() = stiffAssembler.rhs();
        m_system.rhs().middleRows(0,massAssembler.numDofs()) +=
                massAssembler.matrix()*(alpha1()*(solVector-solutionVector).middleRows(0,massAssembler.numDofs())
                                        + alpha2()*velVector + alpha3()*accVector);
    }

    return true;
}

template <class T>
void gsElTimeIntegrator<T>::constructSolution(gsMultiPatch<T> & displacement) const
{
    stiffAssembler.constructSolution(solVector,m_ddof,displacement);
}

template <class T>
void gsElTimeIntegrator<T>::constructSolution(gsMultiPatch<T> & displacement,gsMultiPatch<T> & pressure) const
{
    GISMO_ENSURE(stiffAssembler.numDofs() > massAssembler.numDofs(),
                 "This is a displacement-only formulation. Can't construct pressure");
    stiffAssembler.constructSolution(solVector,m_ddof,displacement,pressure);
}

template <class T>
void gsElTimeIntegrator<T>::saveState()
{
    if (!initialized)
        initialize();
    solVecSaved = solVector;
    velVecSaved = velVector;
    accVecSaved = accVector;
    ddofsSaved = m_ddof;
    hasSavedState = true;
}

template <class T>
void gsElTimeIntegrator<T>::recoverState()
{
    GISMO_ENSURE(hasSavedState,"No state saved!");
    solVector = solVecSaved;
    velVector = velVecSaved;
    accVector = accVecSaved;
    m_ddof = ddofsSaved;
}


} // namespace ends